Patent literature 1: JP 2011-98594 A
Patent literature 1 discloses a load drive apparatus including a basic drive circuit and a backup circuit. The basic drive circuit includes a first MOSFET driving a headlight at a driver seat side and a second MOSFET driving a headlight at a passenger seat side. The backup circuit functions as a failsafe circuit. In the load drive apparatus of Patent literature 1, the backup circuit drives a third MOSFET when there is abnormality in a control circuit and both headlights cannot turn on, so that the headlight at the driver seat side is turned on.
The inventors of the present disclosure have found the following. As described above, the load drive apparatus described in Patent literature 1 includes the third MOSFET for turning on the headlight at the driver seat side in a case when the both of the headlights cannot be turned on. This configuration preliminarily includes a load drive circuit that corresponding to large current to increase cost.
In particular, in recent, a request of a lighting-system load integrated control circuit may be increased, and the lighting-system load integrated control circuit integrally controls a lighting system load such as a headlight and a tail lamp. When a configuration such as the load drive apparatus described in Patent literature 1 is applied to the lighting-system load integrated control circuit, many load drive circuits corresponding to large current such as a third MOSFET may be provided as backup or preliminarily, causing increase of cost further.